Emergency vs Privacy
It is common to leave contact information in passport, contact card in wallet such that under emergency situation, others could notify your family member or significant half. This will be helpful if you are travelling alone, or aged.
But how do we eliminate scam? Our contact information (email, phone number) is perhaps widely shared when register for web service as 2-step authentication, product registration for warranty, leave as call back for inquiry results, or our friends' devices carrying our contacts are compromised.
There is a little trick to beat against scammer by establishing a one-way trust. Put a preset phase in the emergency contact card. Pre-arrange this with your contact(s) the caller must quote this preset phase to prove the contact info is obtained from this emergency contact card but not elsewhere.
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